Nut piercing method



J. H. FRlEDMAN 2,645,793

NUT PIERCING METHOD 5 Sheets-Sheet 1 July 21, 1953 Filed June 17, 1949 July 21, 1953 J. H. FRIEDMAN 2,545,793

` PIERCING mHon Filed June 17, 1949 3 Sheets-Sheet 2 .sz 54 ,1,-53 w Ari-newer:

July 21, 1953 J. H. FRIEDMAN 2,645,793

NUT PIERCING man Arm-r:

Patented July 21, 1953 Jamin. Frieammrrim, ohio, assigner `m'rhe National .Machinery CompanypTln, 'Ohio,'a

corporation of Ohio ApplicationJune17,1943,1seria1N01-9a77o' This invention relates tormethodsV for piercing blanks and is particularly adapted for use in connection with a cold header.

' .11 claims. (C1. 1li-se) This invention 'is particularly advantageous Where the diameter of the v'punched hole is relatively large with regard to the diameter of the' K blank, in which case difficulty has been encountered due to expansion and permanent set ofthe blank as a result of a socketing or punching operation. It is an object of the invention to pierce blanks, such as nut blanks, while cold, without expanding the blanks and With'a minimum of tool wear and breakage. Briefly, thisis accomplished by confining the blank side wall in a sliding die, bringing a punch or tool against the blank, socketing the blank or piercing the blank while conned and vuntil `a slug has broken loose, and if punching, continuing the' punching motion to force the slug clear of the `blank while simultaneously removing 'the confinement of the blank side wall. Thus, the slugf'severing operation takes place While the blank is confined; although the blank may have thin side Walls, it will not be stretched or expanded beyond its elastic limit.

In order to prolong tool wear in accordance with the invention, the punch is withdrawn from the blank after the latter hasbeen Acarried clear of the die by the punch, so that the blank is unconned during the stripping operation. kIn a preferred form of the invention, this is accomplished by stripping mechanism carried vbythe header slide which may be positioned independently of the punch. The punch is stripped rfrom the blank after the latter has been withdrawn clear of the die, which produces little or no wear on the punch. The blank can spring slightly during stripping which facilitates Withdrawal of the punch, but this expansion is not enough to cause a stress that exceeds the'elastic limit, so'that the blank returns to its original diameter. Y f

Another object of the invention is to pcsitivel y and firmly break the'punched slug clear of the nose of the punch after the punch has expelled or pushed the slug into the slug discharge tube. The initial pressure necessary to sever 'the slug from the'blank is often high enoughto cause the slug to adhere firmly to'the punch nose so that the slug tends to be withdrawn with the punch to remain in the blank, instead of being' deposited in the discharge tube provided for the slugs. vInl/a preferred embodiment'of` the inven tion withdrawal of the slug with the punch is cammed radially Aby the shoulder and broken clear of thevpunch nose.V f i Another object fof the invention is to insure that the blank (comes away withthe punch upon retraction of the slide. This is accomplished by.

utilizing motion of 'the punch or tool-carrying means toretract the sliding die that confines the blank after the slugshas been severed from the blank. It is also kan object to accomplish this even though. blank transfer fingers `rmay be at punching operationi- I n the preferred arrange-A ment, theseobjects are attained byy providing one lowing detailed Adescription of a or'more prongsor extensions `n'iovablewit'h the header slide rthat 'stra'ddle or clear the transfer fingers and protrude axially forwardly.- These extensions engage the sliding die or sleeve that surrounds the blank' after the 'slug has been severed from tliefblank by .the'punch land force the dieclear'ofthefblank y l The .mannerinwhich these and 'other lobjects are accomplished will be apparent from the 'folpreferred embodimentof the'l invention. f

In the drawings1` f f yFig'. 1 isa simplified Asection'of a `cold heading device suitable for carrying kout the invention;

' r-Fig. 2' is a fragmentary elevation showing the tool assembly and a 'portion of the transfer fin-v gers;

' Fig. 3 is a `section through the tool and'A die assembly of vthe apparatus disposed yjust as the punching operation f-b`egins; z

' Fig. 4 is a section showing the apparatus just as the slug is severed from the blank;

Fig. 5 shows the vslug broken loose from the end of the punch; and, f

Fig. 6 shows the header-slide 'retracted andthe punch partially'stripped from the blank.

Althoughin itsbroader aspects the invention is not limited to cold-headers, it is particularly adaptabeleto cold heading machines such as that shown'in the patent to Clouse, 1,856,027,.Apri1 26, 1932, and is also applicable to a nut machine such as disclosed in my pending application, Serial No.

663,569, filed April 19;?1916v, now Patent No. 2,-

542,864 granted February 20, 1951. Cold headers adaptable to effecting the invention include generally a die block, arec-iprocable header slide and tools, means to feed stock to the die block, means to shear kolf vblanksV'means totransfer the blanks consistently and ypositively prevented by dispos- I kbetween stations in the die block, means to advance andretract the Aheader slide to perform work on the blanks, and means to knock out the blanksfrom the dies into the transfer means. In

1 Fig. V,1 elements of a cold header essential to an ries the slug against `the .shoulder the slug is yunderstanding .of .the invention `are shown.

As seen in Fig 1, the .header frame Il)` has guides II for reciprocably mounting a slide S. Slide S is reciprocated by the usual crankshaft I2 rotatable in the machine frame which drives the crank or pitman I3 pivoted to the header slide as at I4. In a preferred embodiment of the invention, a cam C is mounted on the crankshaft to control the operation of means to strip the punch from the blank. A roller IB is mounted on a cam follower I1 which is pivoted tothe frame as at I8 and urged by spring apparatus I9 so that the roller bears against the cam. The follower controls a plunger 2|, slidably mounted in the header slide. The combined punching and stripping mechanism 22 is mounted in the header slide, the actual construction thereof being somewhat simplified in Fig. 1. It includes the punch or tool P, an independently movable stripping sleeve 24, and an operating plunger 25 for controlling the sleeve. Suitable transfer mechanism such as that disclosed in my application Serial No. 663,569, filed April 19, 1946, now Patent No. 2,542,864 granted February 20, 1951, operate transfer fingers T to transfer blanks from station to station. A die block 26 and a punch or die station D are also provided which will be described hereinafter in more detail.

Preferred constructional details of the tool and die assemblies are illustrated in Figs. 2 and 3. As seen in those figures, the header slide S has screwed therein a sleeve 3l which acts as a retainer for a bushing 32 having forwardly projecting fingers 33 arranged to pass between the transfer fingers T.

The stripping sleeve 24 surrounds the punch P and slides within the bushing V32. The punch P is retained in the slide by an inner sleeve 34 and a head 35 on the punch shank, these elements being forced against the bushing 32 by means of a plug 36 and a clamping wedge 23 in accordance with practice well known in the art. The plunger 25 has forwardly extending pins 31 which extend through the apertures in the inner sleeve 34 and engage the rearward portion l38 of the stripping sleeve 24.

The die block 25 incorporates special die or punch station mechanism D. A hardened sleeve member 4I is fastened in the die block and slidably mounts a two-part confining sleeve or die member made up of an outer member 42 and an inner hardened blank-confining sleeve or die 43.

The sliding die assembly is retained in the die block by means of narrow clips 44, and are urged Y against the clips by an assembly of plungers 46 and compression springs 41 fitting `within recesses 48 in the sleeve 4I. In order to receive the slug punched from the blank, a discharge tube 5I is mounted centrally in the die station, and includes a slug-receiving passageway 53, a tapered shoulder 54 for breaking the slug clear from the punch, and a slug-receiving mouth 52 concentric with the punch.

In operation, and in accordance with the usual practice, a blank is transferred by the transfer fingers T and their controlling mechanism to a position in front of the sliding die member 43. As the header slide advances, the nose of punch P engages the blank O and forces it into sleeve member 43, springs 41 holding the sleeve member in its outermost position during this operation. As shown in Fig. 1, cam C is contoured so that surface 3| engages the follower I6 during this phase of the cycle and causes the stripping members to move generally forward with the header slide on the advance stroke. The position of the parts in Fig. 3 is such that the punch P has entube.

gaged the blank and forced it against the shoulder of the discharge tube 5I.

Further motion of the header slide causes the punch to pierce and sever the slug 60 from the blank, as seen in Fig. 4. The relationship of parts and the length of fingers 33 is such that just as the slug 60 is severed from the blank, fingers 33 are brought into engagement with the sliding die member 43. It will be noted from Fig. 4 that the blank is confined during the slug severing operation, and even though it has relatively thin walls it cannot expand or stretch past its elastic limit. As advancing motion of the slide continues, the punch forces the slug 60 through the punched blank O1, and fingers 33 force the sliding die 43 clear of the blank. The advancing punch smooths and trues the punched hole, and, as seen in Figs. 4 and 5, I may form the parts so that the blank is unconfined except at the working zone or nose 6I of the punch.

When the punch approaches the end of its stroke, a corner of slug 60 is forced against the tapered or camming surface 54 of the discharge This radially cams the slug and breaks it clear of the nose of the punch to which it tends to adhere or weld, due to the high pressures resulting from punching the confined blank. The punch advances somewhat further than its position in Fig. 5 until the working zone 6I passes through the punched aperture in the blank. As the header slide retracts, this causes the punch to remove the blank from the die block.

Initially, the stripping assembly moves back with the slide, because vthe cam surface 32 of cam C falls away from under the roller I6 as the header slide reti-actsl However, a point is reached wherein the surface 33 of the cam C is turned under the roller I6, which surface is substantially equi-distant from the center of rotation of the crankshaft I2. This causes the stripping plunger `and sleeve apparatus to remain stationary, or substantially so, while the header slide and punch are retracted. As a result, the punch is stripped from the blank which is brought against the forward nose of the stripping sleeve 24 during the stripping operation. It is noted that the stripping operation occurs when the blank has cleared the transfer lingers and while it is unconflned so that no permanent expansion may occur, and wear on the tool is greatly reduced. After the blank has been stripped from the punch the surface 34 of the cam is turned under the follower which permits the entire slide, including the stripping assembly to retract with the header slide. Although I prefer to use a crankshaft-mounted cam to operate the stripping assembly as herein disclosed, any means having a similar mode of operation may be employed to effect independent motion of the punch and stripping sleeve.

Those skilled in the art will recognize that in carrying out the method of this invention, thinwalled blanks can be pierced or punched without danger of permanent expansion of the blanks. However, retraction of the tool is effected while the blanks are unconfined so that tool life is greatly prolonged. Likewise, there is no possibility of the pierced slug being retracted with the tool and blank due to the slug-clearing means formed in the slug-receiving passageway at the die. Furthermore, the tool is stripped from the blank with the blank well clear of the die and transfer fingers so that no interference will be encountered.

The apparatus disclosed herein is claimed in clined surface thereby tilting the slug away from the end of the punch while the blank is cold and while it is coni-"ined, removing the confinement of the blank side wall, and withdrawing the punch j from the blank while the side wall thereof is unconiined.

2. A method of piercing blanks 4comprising the steps of confining the side wall of a. blank s0 that it cannot radially expand, axially punching and severing a slug from the blank while cold and while it is coniined by moving apunch into Vthe blank for less than the full length of the blank and then tilting the slug and, continuing to ad- Vance the punch while simultaneously removing the connement of the blank side wall behind the punch, and withdrawing the punch from the blank While the side wall thereof is unconiined,

3. A method of piercing blanks comprising the' steps of conning the side wall of a blank so that it cannot radially expand, axially punching and severing a slug from the blank While cold and while it is coniinedby moving a punch into the blank for less than the full length of the blank and then tilting the slug and, continuing to advance the punch entirely through the blank while simultaneously removing the confinement of the the punch while simultaneously Lremoving 'the confinement of the ,blank sidewall behind the punch axially'in the direction of punch movement, and withdrawing the punchfromthe blank while the side wall thereof is unconfined.

8. A method of piercing blanks comprising the steps of confining the side wall of a blank so that it cannot radially expand, axially advancing a punch into said blank to severa slugfrom'the blank while it is co'nned, simultaneously removing the confinement of vthe blank side wall behind the head of the punch duringsaid advancing of said punch, continuing to advance the i punch entirely through the blank, withdrawing the punch with the blank thereon, and stripping the punch from the blank while 'the v side wall thereof is unconiined.v

9. A method of piercing blanks comprising the steps of confining the side Wall of 'a blank so that it cannot radially expand, axially advancing a punch into said blank to severa slug from the y blank while it is confined, simultaneously removing the confinement of the blank side wall behind the head of the punch during said advancing of said punch, continuing toadvance the i punch entirely through the blank, breaking theipunched slug loose from the punch while the punch is disposed in the punched hole of the blank, withdrawing the punch with the blank thereon, and stripping the punch from the blank while the side Wall thereof is unconiined.

10. A method of piercing blanks comprising the steps of confining the side wall of a blank so that fit cannot radially expand, axially advancingsa blank side wall behind the punch, withdrawing the punch with the blank thereon from the die, and stripping the punch from the blank while the side Wall thereof is unconfned.

4.r A method of piercing blanks comprising the steps of confining the side wall of a blank so that it cannot radially expand, axially punching and severing a slug from the blank while cold and while it is confined, continuing toadvance the punch entirely through the blank while simultaneously removing the connement of the blank side wall behind the punch, tilting the punched slug loose from the punch with the punch disposed in the punched hole of theblank, withdrawing the punch with theblank thereon from the die, and stripping the punch from'the blank while the side vwall thereof is unconned. l

5. A method of piercing blanks comprising the steps of axially punching the blank with a tool to sever a slug from the blank while cold, forcing the slug partially through the blankinto engagen ment with an inclined surface with the tool thereby radially camming the free end of the slug to break it clear of the nose of the tool.

6. A method of piercing blanks comprising the steps of axially punching the blank with a tool to sever a slug from the blank while cold, forcing the slug partially through the blank with the tool into engagement with an inclined surface thereby tilting the slug clear of the nose of the tool, and withdrawing the tool within the blank thereon afterV the slug is broken clear.

7. A method of piercing blanks comprising the steps of conningthe side wall of a blank so that it cannot radially expand, axially punching and severing a slug from the blank while cold and while it is confined, continuing to advance punch into said blank while it is coniined, simultaneously removing the .confinement of the blank sidewall behind the head ofthe punchduring said advancing of said punch, continuing Vto re- 7 move the confinement of the blank sidewall, withdrawing the punch with the blank thereon, and stripping the punchfrom the blank 'while the side wall thereof is unconned.

11. A method of piercing a blank comprising the'steps of confining the side wall of a blank in a die opening, forcing a punch into said blank by relative axial movement of the punch and blank in one direction while the sidewall of the blank is coniined,'simultaneously removing the confinement ofthe blank side wall behindk the head of the punch during said advancing of said f punch by axial motion of said die relative to said blank in the same direction as the axial motion of said punch relative to said blank continuing the relative axial movement of said blank and said die to free the side wall of the pierced blank from said die, and stripping the punch'from the blank while the side wallof the blank is vunconnned by axial motion of the punch relative to said blank in the opposite direction rfrom said JOHN H. FRIEDMAN.

one direction.

References cited inthe me of this patent UNITED STATES PATENTS 

